1. Technical Field
Example embodiments of the present invention relate in general to protection switching in a network, and more particularly, to a shared mesh protection switching apparatus and method that can be applied to a network topology environment in which ends of different linear protection paths are disposed at the same node.
2. Related Art
Protection switching is a method for resuming traffic as soon as possible when a network failure stops the traffic. Protection switching can be classified into linear protection switching, ring protection switching, and mesh protection switching according to network topology.
In linear protection switching, a working path and a protection path are set not to intersect for traffic flowing in both directions or in one direction between two points. At normal times, traffic is transferred through the working path, but when a network failure occurs or according to control of an administrator, traffic is transferred through the protection path.
Linear protection switching is performed in one linear protection domain. In other words, in linear protection switching, both ends of traffic and a working path and protection path connecting the ends are defined as one linear protection domain, and messages are exchanged according to a protocol between the ends, so that a protection switching function operates.
Mesh protection switching sets one linear protection domain for each point-to-point (P2P) connection and enables protection paths of a plurality of linear protection domains to share the same network resources when a plurality of P2P connections are established in a mesh topology network.
In other words, countless linear protection domains having different ends are present in a mesh topology network, and mesh protection switching provides a mechanism capable of tuning use of network resources between linear protection domains, so that protection paths of the respective linear protection domains can share the network resources.
FIG. 1 illustrates an example of a general mesh protection switching operation.
Referring to FIG. 1, two linear protection domains are set for two P2P connections (i.e., A-B and C-D) in a mesh topology, respectively. Here, a working path W1 and a protection path P1 (i.e., A-P-Q-B) are for a P2P connection A-B of a first linear protection domain.
On the other hand, a working path W2 and a protection path P2 (i.e., C-P-Q-D) are for a P2P connection C-D of a second linear protection domain.
To enable the two protection paths P1 and P2 to share network resources of a section P-Q between a node P and a node Q, mesh protection switching specifies exchange and processing of protocol messages between the end nodes (i.e., the nodes A, B, C and D) of the connections and the shared nodes (i.e., the nodes P and Q).
In general, existing mesh protection switching as illustrated in FIG. 1 specifies protocol messages required upon a network failure and the resultant process on the assumption that the connection end nodes (i.e., the nodes A, B, C and D) differ from the shared nodes (i.e., the nodes P and Q). However, when a connection end node is a shared node, existing mesh protection switching cannot be applied, and appropriate mesh protection switching for this environment is required.